Phonon-assisted relaxation and tunneling in self-assembled quantum dot molecules

TL;DR

This paper theoretically investigates phonon-assisted relaxation and tunneling in self-assembled quantum dot molecules, revealing how phonon interactions influence electron dynamics and thermalization times.

Contribution

It introduces a detailed theoretical model combining k.p approximation and Coulomb interactions to analyze phonon-assisted processes in quantum dot molecules.

Findings

Relaxation occurs on a picosecond timescale.

Both deformation potential and piezoelectric couplings are significant.

Thermalization depends on quantum dot size and parameters.

Abstract

We study theoretically phonon-assisted relaxation processes in a system consisting of one or two electrons confined in two vertically stacked self-assembled quantum dots. The calculation is based on a k.p approximation for single particle wave functions in a strained self-assembled structure. From these, two-particle states are calculated by including the Coulomb interaction and the transition rates between the lowest energy eigenstates are derived. We take into account phonon couplings via deformation potential and piezoelectric interaction and show that they both can play a dominant role in different parameter regimes. Within the Fermi golden rule approximation, we calculate the relaxation rates between the lowest energy eigenstates which lead to thermalization on a picosecond time scale in a narrow range of dot sizes.